1. Technical Field
The present invention relates generally to an apparatus including a joystick for steering a small watercraft having a jet drive engine and an outdrive.
2. Background Information
There are many different types of watercraft steering apparatus, each of which includes a steering device and a marine propulsion device. Examples of steering devices include rotary steering devices and tiller handles for rotating and holding outboard motors in different positions. Examples of marine propulsion devices include stern drives, outboard motors, shafted propellers, surface drives, and waterjets.
A waterjet is normally affixed to the bottom of boat's hull and rearwardly discharges a stream of high velocity water to impel a boat forward. Water, traveling at the speed of the boat, enters an intake and continues onto a pumping unit. Within the pumping unit, a spinning impeller, powered by the boat's engine, increases the pressure of the water. The water then exits the waterjet through a nozzle as a high velocity stream, which drives the boat forward. The direction of the high velocity water stream from the waterjet determines the direction of propulsion of the boat. A boat driver operates a rotary steering device or the like to manipulate the direction of the high velocity water stream.
A waterjet is in many ways superior to other types of marine propulsion devices. It imparts superior maneuverability to a boat, and is efficient and easy to install. Additionally, a waterjet has a simple design, low drag, and a shallow draft. It is easy to maintain, smooth and quiet, and does not endanger people in the water like an exposed propeller would. Lastly, a waterjet maximizes the life of an engine, since its impeller is matched to the boat's engine power, and the waterjet will not overload the boat's engine. A watercraft with a waterjet propulsion device is therefore highly desirable.
Unfortunately, rotary steering systems commonly used in waterjet propelled watercraft, such as leisure-type powerboats, typically have a steering column that extends between a steering wheel and a mechanical housing. Rotary steering systems typically have a completely enclosed mechanical housing, which cannot be readily opened for servicing. A need therefore exists for a steering system that is easy to service.
Like a steering wheel in an automobile, installing a steering wheel in a waterjet propelled watercraft is popular because its use is generally intuitive. Although popular, steering wheels rely on converting rotational movement to linear movement. A waterjet requires application of a linear force and linear movement to effect steering. Devices for achieving this may be, for example, a rack and pinion drive. One of the disadvantages of having to convert rotary motion into linear motion is that the apparatus generally required for this purpose is relatively expensive to manufacture. For example, worm gear drives or rack and pinion drives require many machined components.
Another disadvantage relates to the steering rate, that is, the amount of rotation of the waterjet for a given number of degrees of rotation of the steering wheel. A steering apparatus using a worm drive may require several revolutions of the steering wheel to provide a relatively short output movement, thus making it unsuitable for applications requiring fast steering response such as racing.
Yet another disadvantage of the prior art steering apparatus relates to its size and weight. Such systems are generally too heavy and bulky to be useful in, for example, a personal watercraft.